Display module and system applications

ABSTRACT

A display module and system applications including a display module are described. The display module may include a display substrate including a front surface, a back surface, and a display area on the front surface. A plurality of interconnects extend through the display substrate from the front surface to the back surface. An array of light emitting diodes (LEDs) are in the display area and electrically connected with the plurality of interconnects, and one or more driver circuits are on the back surface of the display substrate. Exemplary system applications include wearable, rollable, and foldable displays.

RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/157,235, filed May 17, 2016, which is a continuation of U.S.patent application Ser. No. 14/109,864, filed on Dec. 17, 2013, now U.S.Pat. No. 9,367,094 which is incorporated herein by reference.

BACKGROUND

Field

The present invention relates to display modules. More particularlyembodiments of the present invention relate to display module packagesand system applications thereof.

Background Information

Light emitting diodes (LEDs) are increasingly being considered as areplacement technology for existing light sources. For example, LEDs arefound in signage, traffic signals, automotive tail lights, mobileelectronic displays, and televisions. Some specific mobile electronicsare smart electronic devices, such as smartphones, smartwatches, etc.including more advanced computing capability than a feature phone orwatch. Demand is increasing for thinner, lighter weight, and lower costsmart electronic devices, with higher resolution and larger touchscreens. Organic light emitting diode (OLED) display and liquid crystaldisplay (LCD) are the two most widely adopted display technologies incurrent smart electronic devices.

OLED technology generally includes a layer of an organic compound in apixel area, and a thin film transistor (TFT) backplane to switch eachindividual pixel on or off. An OLED display works without a backlightand can display deep black levels. The organic compound layer issensitive to air and moisture, which can lead to degradation of thedisplay. OLED displays are typically encapsulated with a rigid glasscover to protect the organic compound from air and moisture.

LCD technology generally includes pixels filled with liquid crystals,and a thin film transistor (TFT) backplane to switch each individualpixel on or off. Since the liquid crystals do not produce light bythemselves, they need backlight illumination from behind or side of thedisplay panel.

Two widely adopted manners for packaging display modules based on OLEDor LCD include chip-on-glass (COG) packaging and chip-on-film (COF)packaging. FIGS. 1A-1B are exemplary schematic cross-sectional side viewand schematic front view illustrations of a COG packaged display module.As illustrated, the display module 100 includes a display panel 115connected to a printed circuit board (PCB) 106 by a flexible printedcircuit (FPC) 108. The display panel 115 includes a display substrate102 formed of either OLED or LCD display technologies, one or moredriver ICs 110 mounted on the display substrate 102 and a cover 114 overthe display substrate. A seal ring 113 may surround the display area 101of the display substrate for attaching the cover 114 and sealing thedisplay area 101 from air and moisture. In smart electronic devices thedisplay substrate 102 may additionally include a touch screen within thedisplay area 101. Alternatively a touch screen can be formed over thedisplay substrate 102. In the case of LCD display technology, abacklight 105 is located behind the display substrate.

Additional devices and IC chips 104 for operating the display module 100are located off of the display substrate 102 on PCB 106. For example, ICchips 104 can include a power management IC, processor, timingcontroller, touch sense IC, wireless controller, communications IC, etc.As illustrated, the PCB 106 is connected to the display substrate 102with FPC 108, with contact areas 107 of the FPC 108 bonded to surfacesof the display substrate 102 and PCB 106. Referring to both FIGS. 1A-1B,the area reserved on the display substrate for the one or more driverICs 110 and contact area 107 are referred to as a contact ledge 111. ThePCB 106 may extend laterally from the display substrate 102, oralternatively can be wrapped behind the display substrate asillustrated. As shown in FIGS. 1A-1B, a lateral extension length 109 ofthe FPC 108 may be associated with the FPC 108 of the display module,even where the PCB 106 is wrapped behind the display substrate 102. Abattery 112 may also be located behind the display substrate with thePCB 106.

COF packaging is similar to COG packaging, with one main differencebeing that the one or more driving ICs 110 are moved from the displaysubstrate 102 onto the FPC 108. In such applications, the contact ledgemay require less space than COG packaging.

SUMMARY OF THE INVENTION

Display module packages and system applications thereof are described.In an embodiment, a display module includes a display substrate having afront surface, a back surface, and a display area on the front surface.A plurality of interconnects extend through the display substrate fromthe front surface to the back surface, and an array of LEDs are in thedisplay area and electrically connected with the plurality ofinterconnects. One or more driver circuits are on the front surface orthe back surface of the display substrate. In an embodiment, theplurality of interconnects extend through the display substrate from thefront surface to the back surface directly behind the display area, andthe one or more driver circuits are on the back surface of the displaysubstrate. In an embodiment, a flexible printed circuit does not connectthe one or more driver circuits to the display substrate.

The plurality of interconnects may be through vias that extend throughthe display substrate from the front surface to the back surface. Theinterconnects can be used for a variety of applications, for example, aground via. A variety of devices can be located on the front or backsurfaces of the display substrate. For example, a battery can be locatedon a back surface of the display substrate. In an embodiment, an arrayof micro chips are located on the front surface of the display substrateand within the display area. The array of micro chips may beelectrically connected with the plurality of interconnects and the arrayof LEDs. In some embodiments, the array of micro chips overlaps theplurality of interconnects. In other embodiments, the array of microchips do not overlap the plurality of interconnects. In an embodiment,the array of micro chips includes an array of ambient light sensors. Auniform distribution of ambient light sensors can be located in thearray of micro chips.

In accordance with embodiments of the invention the display module canbe incorporated into a wearable electronic device, for example, asmartwatch. In such an embodiment, the display area of the displaysubstrate spans a watch face and a band of the smartwatch. In anotherembodiment, the display substrate is secured to a spool. In such anembodiment, the spool can include the one or more driver circuits inelectrical contact with the plurality of interconnects. In oneapplications, the display module can be incorporated into a television.

In an embodiment, a non-transitory computer-readable medium storesinstructions which, when executed by a processor, cause the processor toperform operations to adjust display data for a display area of awearable electronic device. The operations include receiving input forma control device, with the input including data for the display area ofthe wearable electronic device. The input is parsed to derive the datafor display, and the derived data is displayed on the display area,where the display area is on a flexible display substrate spanning aface and band of the wearable electronic device. For example, thewearable electronic device may be a smartwatch. In an embodiment, thenon-transitory computer-readable medium stores additional instructionsto perform additional operations including receiving a configuration ofthe display area of the watch face and band, receiving a design from thederived data, the design including a watch face and watch band, andupdating the display area with the received design.

In an embodiment, a display module for a wearable electronic deviceincludes a flexible display substrate spanning a face and a band of thewearable electronic device. An accessory manager is coupled to thedisplay substrate, to receive input form a control devicecommunicatively coupled to the display module. The display moduleadditionally includes a graphical user interface (GUI) manager, tocontrol information displayed on the display substrate, where thedisplay substrate includes a first display area associated with a faceof the wearable electronic device and a second display area associatedwith a band of the wearable electronic device. In an embodiment, the GUImanager is to further provide a watch face design to the first displayarea and a watch band design to the second display area. In anembodiment, the accessory manager is to further receive input data froma control device via a communication module, the input data includingconfiguration data for the GUI manager.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic cross-sectional side view illustration of a COGpackaged display module.

FIG. 1B is a schematic front view illustration of a COG packaged displaymodule.

FIG. 2A is a schematic cross-sectional side view illustration of adisplay substrate including a plurality of interconnects in accordancewith an embodiment of the invention.

FIG. 2B is a schematic cross-sectional side view illustration of adisplay substrate including a plurality of through vias in accordancewith an embodiment of the invention.

FIG. 3 is a schematic cross-sectional side view illustration of adisplay substrate including an array of LEDs and micro chips in adisplay area on a front surface of the display substrate in accordancewith an embodiment of the invention.

FIG. 4 is a schematic cross-sectional side view illustration of adisplay module including one or more driver circuits on the back surfaceof the display substrate directly behind the display area in accordancewith an embodiment of the invention.

FIG. 5A is a schematic front view illustration of a display substrateincluding an array of LEDs and micro chips in a display area and aplurality of through vias directly beneath the display area, where thearray of micro chips overlap the plurality of through vias in accordancewith an embodiment of the invention.

FIG. 5B is a schematic back view illustration of a display substrateincluding one or more driver circuits on the back surface of the displaysubstrate and a plurality of through vias directly behind the displayarea in accordance with an embodiment of the invention.

FIG. 5C is a schematic front view illustration of a display substrateincluding an array of LEDs and micro chips in a display area and aplurality of through vias directly beneath the display area, where thearray of micro chips do not overlap the plurality of through vias inaccordance with an embodiment of the invention.

FIG. 5D is a schematic front view illustration of a display substrateincluding an array of LEDs and micro chips in a display area and aplurality of through vias outside of the display area in accordance withan embodiment of the invention.

FIG. 6A is a schematic cross-sectional side view illustration of TFTdisplay substrate including one or more through vias in accordance withan embodiment of the invention.

FIG. 6B is a schematic cross-sectional side view illustration of a TFTdisplay substrate and display module including an array of LEDs in adisplay area and one or more through vias outside of the display area inaccordance with an embodiment of the invention.

FIGS. 7A-7B are schematic front view illustration of a TFT substrate anddisplay module including one or more driver circuits in contact with oneor more through vias outside of the display area in accordance withembodiments of the invention.

FIG. 8 is a schematic front view illustration of a TFT display substrateand display module including an array of LEDs and a plurality of throughvias in accordance with an embodiment of the invention.

FIG. 9 is a schematic front view illustration of a wearable electronicdevice including a display panel in accordance with an embodiment of theinvention.

FIGS. 10-12 are perspective view illustrations of a wearable electronicdevice displaying various display images in accordance with embodimentsof the invention.

FIG. 13 is a system diagram of a wearable electronic device having adisplay panel in accordance with an embodiment of the invention.

FIG. 14 is schematic cross-sectional side view illustration of a systemincluding a flexible display panel secured to a spool in accordance withan embodiment of the invention.

FIG. 15 is a schematic cross-sectional side view illustration of aflexible display panel including an array of LEDs and micro chips in adisplay area on a front surface of the display substrate in accordancewith an embodiment of the invention.

FIG. 16 is a schematic front view illustration of a flexible displaypanel including two areas of micro chips exposed to different levels ofambient light in accordance with an embodiment of the invention.

FIG. 17 is a system diagram of a display system including the flexibledisplay panel in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention describe display module packagingconfigurations and system applications thereof. In an embodiment, adisplay module includes a display panel which includes a displaysubstrate with a front surface, a back surface, and a display area onthe front surface. A plurality of interconnects extend through thedisplay substrate from the front surface to the back surface, and areelectrically connected with an array of LEDs are on the front surface ofthe display substrate. For example, each interconnect may be a singlethrough via, or a series of interconnect lines and vias through multiplelayers. One or more driver circuits are located on the front or backsurfaces of display substrate and in electrical connection with theplurality of interconnects. In an embodiment the one or more drivercircuits are located on the back surface of the display substrate. In anembodiment, the one or more driver circuits are located on the backsurface of the display substrate directly behind the display area on thefront surface of the display substrate.

In various embodiments, description is made with reference to figures.However, certain embodiments may be practiced without one or more ofthese specific details, or in combination with other known methods andconfigurations. In the following description, numerous specific detailsare set forth, such as specific configurations, dimensions andprocesses, etc., in order to provide a thorough understanding of thepresent invention. In other instances, well-known semiconductorprocesses and manufacturing techniques have not been described inparticular detail in order to not unnecessarily obscure the presentinvention. Reference throughout this specification to “one embodiment”means that a particular feature, structure, configuration, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in one embodiment” in various places throughout thisspecification are not necessarily referring to the same embodiment ofthe invention. Furthermore, the particular features, structures,configurations, or characteristics may be combined in any suitablemanner in one or more embodiments.

The terms “spanning”, “over”, “to”, “between” and “on” as used hereinmay refer to a relative position of one layer with respect to otherlayers. One layer “spanning”, “over” or “on” another layer or bonded“to” or in “contact” with another layer may be directly in contact withthe other layer or may have one or more intervening layers. One layer“between” layers may be directly in contact with the layers or may haveone or more intervening layers.

In one aspect, embodiments of the invention enable the fabrication ofdisplay panels and display modules with a reduced form factor in the x-yand z directions compared to COG and COF display module packagingconfigurations. In an embodiment, the x-y and z form factors are reducedcompared to COG and COF display module packaging configurations byconnecting the one or more driver circuits to interconnects, for examplethrough vias, extending through the display substrate from the frontsurface to the back surface rather than with a FPC. Furthermore, thepackaging approaches in accordance with embodiments of the invention mayimprove system performance due to shorter interconnects betweencomponents.

In an embodiment, the x-y form factor (e.g. length-width) is reducedcompared to COG and COF display module packaging configurations byremoving or reducing the contact ledge area that would otherwise bereserved for one or more driver ICs 110 on the display area side of thedisplay substrate, contact area of the FPC to the display substrate,and/or the lateral extension length associated with the FPC whenpositioned lateral to the display substrate 102 or wrapped around andbelow the display substrate. In accordance with embodiments of theinvention, such a reduction of the x-y form factor may also allow for anincreased allocation of display area on the display substrate. Forexample, COG packaging may require a contact ledge of at least 4-5 mm toallocate the driver ICs and FPC contact area. In accordance withembodiments of the invention, it is not required to allocate space fordriver ICs and a FPC. In this manner a bevel width around the displayarea can be reduced below 1 mm, for example less than 0.5 mm.

In an embodiment, the z form factor (e.g. thickness) is reduced comparedto COG and COF display module packaging configurations by removing theFPC and PCB. In accordance with embodiments of the invention, aplurality of interconnects, for example though vias, extend through thedisplay substrate from the front surface to the back surface to connectthe driver ICs and any additional IC chips including a power managementIC, processor, timing controller, touch sense IC, wireless controller,communications IC, etc. In this manner, the chips and circuits foroperating the display panel and module can be located on the backsurface of the display substrate, eliminating the thickness of a PCB. Inmany embodiments, the driver ICs and additional IC chips are locateddirectly behind the display area.

In some embodiments, the display panel includes a plurality ofsemiconductor-based LEDs in the display area. Such a configuration mayenable the use of interconnects or through vias that otherwise may beproblematic with the widely adopted LCD or OLED display technologies.For example, through vias and the placement of ICs on the back surfaceof the display substrate could be particularly problematic withconventional LCD technology which includes liquid crystals in thedisplay area and requires the use of backlighting. Through vias couldalso be particularly problematic with existing OLED display technologieswhere through vias could potentially lead to air or moisture exposure.Though it is to be appreciated that some embodiments of the inventionmay be compatible with OLED display technology.

In another aspect, embodiments of the invention describe packagingconfigurations of flexible display panels into flexible display modulesthat can be incorporated into a variety of applications. In oneapplication, embodiments of the invention describe a wearable electronicdevice, such as a smartwatch, including a flexible display panel andflexible display module. In this manner, the display area of thesmartwatch is not limited to a rigid watch face area. In an embodiment,a smartwatch includes a flexible display panel that is integrated into aflexible watch band. Accordingly, curvature of the flexible displaypanel in both the watch face area and band may be adjusted to conform tothe wrist size of the user. In addition, it is not required to include aFPC attached to the display area side of the display substrate. In thismanner, the display area of the flexible display panel can cover moreavailable space on the watch face area and band of the smartwatch.

The wearable electronic device may include a non-transitory computerreadable medium including computer code for receiving a user input froma control device and adjusting display data for the display area of thewearable electronic device. For example, in one application, the usermay select a specific watch design to be displayed on the display panelof the smartwatch spanning a watch face and band of the smartwatch. Uponreceiving the user input from a control device such as a computer, orportable electronic device such as a smartphone, the display data forthe display area of the wearable electronic device is adjusted.

In another application, the flexible display panel is rollable. Forexample, the display panel may be incorporated into a television displaythat is rollable or foldable into and out of a housing. In anembodiment, the flexible television display panel is coupled to a spoolonto which the display panel is rollable or foldable. In an embodiment,the driver ICs and/or any additional IC chips including a powermanagement IC, processor, timing controller, touch sense IC, wirelesscontroller, communications IC, etc. can be relocated to the spool andelectrically connected with the flexible television display panel with aredistribution layer on the back surface of the flexible televisiondisplay panel. The driver ICs and any additional IC chips canalternatively be located on the back surface of the display panel. Inanother application, the flexible display panel is foldable. Forexample, the display panel may be incorporated into a smartphone ortablet and folded into various configurations.

FIG. 2A is a schematic cross-sectional side view illustration of adisplay substrate including a plurality of interconnects in accordancewith an embodiment of the invention. As illustrated, the displaysubstrate 202 may include a front surface 203, a back surface 205, and adisplay area 201 on the front surface. A plurality of interconnects 204,206 extend through the display substrate from the front surface 203 tothe back surface 205 directly behind the display area 201. Asillustrated, each interconnect 204, 206 may be a series of interconnectlines 207A and vias 207B through multiple layers of a multi-layerdisplay substrate 202. Referring to FIG. 2B, each interconnect 204, 206may be a single through via formed through the display substrate 202,which may be a single or multi-layer display substrate 202. In interestof conciseness, the flowing description and figures refer tointerconnect features 204, 206 as through vias. It is to be appreciatedhowever, that such a configuration references an embodiment, and thatwhen referring to through vias 204, 206, these may be replaced byinterconnects including a series of interconnect lines and vias throughmultiple layers of a multi-layer display substrate. Through vias 204,206 may be formed using a variety of techniques including, but notlimited to, chemical etching or laser drilling.

Display substrate 202 can be formed from a variety of materialsincluding glass, amorphous silicon, polysilicon, single crystal silicon,metal foil, metal foil covered with dielectric, or a polymer such aspoly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET),polyethelyne naphthalate (PEN), polycarbonate (PC), polyethersulphone(PES), aromatic fluorine-containing polyarylates (PAR), polycyclicolefin (PCO), and polyimide (PI). In an embodiment, display substrateincludes a polymer-silicon stack. In an embodiment, display substrate202 is a flexible glass substrate. For example, display substrate 202may be a flexible boro-silicate glass substrate. One exemplary flexibleglass substrate is manufactured under the tradename WILLOW™ glass byCorning Incorporated located in Corning, N.Y.

In the embodiments illustrated, a redistribution layer 208 is formed onthe back surface 205 of the display substrate. Redistribution layer mayinclude a single layer or a plurality of layers including wiring 210A,210B. For example, wiring 210A can be used to for electrical contactwith an array of LEDs formed on the top surface 203 of the displaysubstrate 202 with one or more through vias 204, while wiring 210B maybe used for a Vss connection with one or more through vias 206. In anembodiment, the one or more through vias 204, 206 are directly behindthe display area 201. The one or more through vias 204, 206 may also belocated outside of the display are 201, such as along a periphery of thedisplay area 201 on the top surface 203 of display substrate 202.

A wiring layer 212 may also be located on the top surface 203 of displaysubstrate 202 in electrical contact with the plurality of through vias204. Wiring layers 212, 210A, 210B and vias 204, 206 may be formed ofany suitable electrically conductive material used in packagingapplications including metals films, conductive polymers, conductiveoxides, etc. Referring now to FIG. 3, in accordance with an embodimentof the invention and array of LED devices 214 and optionally micro chips216 may be transferred and bonded to the display substrate 202. Forexample, the array of LED devices 214 and micro chips 216 may be inelectrical connection with the plurality of through vias 204.

In accordance with embodiments of the invention, the LED devices 214 aresemiconductor-based LED devices including one or more active layers(e.g. quantum well layers) between two doped semiconductor claddinglayers. In the particular embodiments illustrated, the LED devices 214are vertical LED devices in which the layers are horizontal, and thelayers are stacked vertically. Top and bottom conductive contacts areformed on the vertical LED devices in order to make electrical contactwith the top contact layers 220 described in further detail with regardto FIG. 4 below and wiring layer 212, respectively. In anotherembodiment, the LED devices 214 are horizontal LED devices in which thecontacts to the doped cladding layers are both formed on the bottomsurface of an LED device in order to make electrical contact with wiringlayer 212.

In accordance with embodiments of the invention, the micro chips 216replace the TFT layer of a conventional active matrix display to switchand drive one or more LED devices 214. In one embodiment, each microchip 216 couples with one or more red, green, and blue LED devices 214that emit different colors of light. In such an exemplary red-green-blue(RGB) sub-pixel arrangement, each pixel includes three sub-pixels thatemit red, green, and blue light. The RGB arrangement is exemplary andembodiments are not so limited. For example, alternative sub-pixelarrangements include red-green-blue-yellow (RGBY),red-green-blue-yellow-cyan (RBGYC), red-green-blue-white (RGBW), orother sub-pixel matrix schemes where the pixels have a different numberof sub-pixels, such as displays manufactured under the trademark namePenTile®. In the exemplary embodiments illustrated in the followingdescription, a single micro chip 216 is illustrated as controlling twopixels. It is to be appreciated that this configuration is likewiseexemplary and embodiments are not so limited. For example, each microchip 216 can switch and drive one or more LED devices 214 arranged inseries, in parallel, or a combination of the two, such that multiple LEDdevices are driven from the same control signal. A variety ofalternative configurations are contemplated in accordance withembodiments of the invention. In other embodiments, sensors such astouch sensors or light sensors can also be located on the front surfaceof the display substrate within the display area similarly as the microchips.

In one aspect, embodiments of the invention describe display panels anddisplay module packaging configurations in which micro LED devicesand/or micro chips are transferred and bonded to a wiring 212 using anelectrostatic transfer head assembly. In accordance with embodiments ofthe present invention, a pull-in voltage is applied to an electrostatictransfer head in order to generate a grip pressure on a micro LED deviceor micro chip. It has been observed that it can be difficult toimpossible to generate sufficient grip pressure to pick up micro deviceswith vacuum chucking equipment when micro device sizes are reduced belowa specific critical dimension of the vacuum chucking equipment, such asapproximately 300 μm or less, or more specifically approximately 100 μmor less. Furthermore, electrostatic transfer heads in accordance withembodiments of the invention can be used to create grip pressures muchlarger than the 1 atm of pressure associated with vacuum chuckingequipment. For example, grip pressures of 2 atm or greater, or even 20atm or greater may be used in accordance with embodiments of theinvention. Accordingly, in one aspect, embodiments of the inventionprovide the ability to transfer and integrate micro LED devices andmicro chips into applications in which integration is not possible withcurrent vacuum chucking equipment. In some embodiments, the term “micro”chip, “micro” LED device, or other “micro” structure may refer to thedescriptive size, e.g. length or width, of certain devices orstructures. In some embodiments, “micro” chips or “micro” LED devicesmay be on the scale of 1 μm to approximately 300 μm or less, or 100 μmor less in many applications. However, embodiments of the presentinvention are not necessarily so limited, and certain aspects of theembodiments may be applicable to larger micro devices or structures, andpossibly smaller size scales.

Referring now to FIG. 4, following the transfer and bonding of thearrays of LEDs 214 and micro chips 216 a passivation layer 218 may beprovided between the LEDs 214 and covering the wiring layer 212 followedby the deposition of a top contact layer 220. In an embodiment, topcontact layer 220 may be in electrical contact with a Vss line or Vssplane, for example that may be in electrical connection with the one ormore through vias 206. Alternatively the Vss line or Vss plane may belocated on the top surface 203 of the display substrate 202. Followingthe formation of top contact layer 220, an encapsulation layer 222 maybe formed over the display substrate. In some embodiments theencapsulation layer 222 may be a flexible encapsulation layer.

In accordance with embodiments of the invention, passivation layer 218may be transparent or semi-transparent to the visible wavelength so asto not significantly degrade light extraction efficiency of thecompleted system. Passivation layer 218 may be formed of a variety ofmaterials such as, but not limited to epoxy, poly(methyl methacrylate)(PMMA), benzocyclobutene (BCB), polyimide, and polyester. In anembodiment, passivation layer 218 is formed by ink jetting around theLEDs 214.

Depending upon the particular application, top contact layer 220 may beopaque, reflective, transparent, or semi-transparent to the visiblewavelength. For example, in top emission systems the top contact layer220 may be transparent, and for bottom emission systems the topconductive contact may be reflective. Exemplary transparent conductivematerials include amorphous silicon, transparent conductive oxides (TCO)such as indium-tin-oxide (ITO) and indium-zinc-oxide (IZO), carbonnanotube film, or a transparent conductive polymer such aspoly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline, polyacetylene,polypyrrole, and polythiophene. In an embodiment top conductive contactlayer 220 is approximately 50 nm-1 μm thick ITO-silver-ITO stack. In anembodiment, the top conductive contact layer 220 includes nanoparticlessuch as silver, gold, aluminum, molybdenum, titanium, tungsten, ITO, andIZO. In a particular embodiment, the top conductive contact 220 isformed by ink jetting. Other methods of formation may include chemicalvapor deposition (CVD), physical vapor deposition (PVD), spin coating.

In embodiments where top conductive layer 220 is transparent, the topencapsulation layer 222 may also be transparent or semi-transparent soas to not degrade light extraction efficiency of the system. Topencapsulation layer 222 may be formed of a variety of materials such as,but not limited to, silicon oxide (SiO₂), silicon nitride (SiN_(x)),poly(methyl methacrylate) (PMMA), benzocyclobutene (BCB), polyimide, andpolyester, and may be formed by a variety of methods including chemicalvapor deposition (CVD), physical vapor deposition (PVD), spin coating.

Still referring to FIG. 4, in accordance with embodiments of theinvention, driver ICs 230 and additional devices and IC chips 234 foroperating the display module 200 are located on the back surface 205 ofthe display substrate 102 of the display panel 215. For example, ICchips 234 can include a power management IC, processor, memory, timingcontroller, touch sense IC, wireless controller, communications IC, etc.As illustrated, the driver ICs 230 and additional IC chips 234 may belocated on the back surface of the display substrate directly behind thedisplay area 201. In one embodiment, a battery 238 may also be formed onRDL 208 on the back surface 205, or alternatively a thin film battery238 can be formed on the array of IC chips 230, 234.

In an embodiment, the driver ICs 230 are in electrical connection withwiring 210A in RDL 208, which are in electrical connection withinterconnects illustrated as through vias 204 extending between thefront surface and back surface of the display substrate 202, which arein electrical connection with wiring layer 212 on the top surface ofdisplay substrate 202, which is in electrical connection with the LEDs214 and optional micro chips 216. In an embodiment wiring layer 212includes scan lines, which are coupled to one or more scan driver ICs230, and data lines which are coupled to one or more data driver ICs 230located on the back surface 205 of the display substrate 202 throughvias 204. The LEDs 214 may each be coupled to a common Vss through athrough via 206, or a plurality of through vias 206.

FIG. 5A is a schematic front view illustration of a display substrate202 including an array of LEDs 214 and micro chips 216 in a display areaand a plurality of through vias 204, 206 directly beneath the displayarea, where the array of micro chips overlap the plurality of throughvias in accordance with an embodiment of the invention. As shown in FIG.5A, the display area 201 may include the entire surface of displaysubstrate 202, or at least the maximum amount of surface possible forplacing the LEDs and micro chips. Through vias 204 may be connected toany of the chips 230, 234 on the back surface of the display substrate202. For example, through vias 204 may connect a micro chip 216 to adata line, scan line, Vdd, clock, etc. In the particular embodimentillustrated through vias 204 are directly beneath the array of microchips 216, and Vss through vias 206 are interspersed through the displayarea between the micro chips 216. FIG. 5B is a schematic back viewillustration of a display substrate 202 including one or more drivercircuits 230 on the back surface of the display substrate and aplurality of through vias 204, 206 directly behind the display area inaccordance with an embodiment of the invention. As shown a number ofadditional IC chips 234 and battery 238 may also be located directlybehind the display area.

FIG. 5C is schematic front view illustration of a display substrateincluding an alternative arrangement of an array of LEDs and micro chipsin a display area 201 and a plurality of through vias directly beneaththe display area 201, where the array of micro chips 216 do not overlapthe plurality of through vias 204, 206 in accordance with an embodimentof the invention. For example, the plurality of through vias 204, 206can be interspersed between the micro chips 216 as illustrated in FIG.5C. In the exemplary embodiment illustrated in FIG. 5C, wiring 212 isillustrated connecting the plurality of through vias 204 and LEDs 214 tothe array of micro chips 216.

FIG. 5D is a schematic front view illustration of a display substrateincluding an array of LEDs and micro chips in a display area 201 and aplurality of through vias outside of the display area 201 in accordancewith an embodiment of the invention. As shown in FIG. 5D, the displayarea 201 may be smaller than the front surface of display substrate 202,and the plurality of through vias 204, 206 are located along a peripheryof the display substrate 202 outside of the display area 201. In theexemplary embodiment illustrated in FIG. 5D, wiring 212 has not beenillustrated for connecting the plurality of through vias 204 to themicro chips 216 in order to not obscure the illustration.

Referring now to FIGS. 6A-8, the packaging configurations in accordancewith embodiments of the invention are applied to an existing OLEDdisplay panel 315 to form a display module 300. In the embodimentillustrated in FIG. 6A, a display substrate 302 is a TFT backplaneincluding working circuitry 316 and organic LEDs 314. Exemplary TFTworking circuitries 316 may include amorphous-silicon based,poly-silicon based, and indium-gallium-zinc-oxide based technologies. Inan embodiment, through vias 304 can be formed through the displaysubstrate in the contact ledge area 311 that is conventionally reservedfor driver ICs and a FPC. Referring now to FIG. 6B, similar to theprevious embodiments described and illustrated, additional devices andIC chips 334 for operating the display module 300 are located on theback surface 305 of the display substrate 302. For example, IC chips 334can include a power management IC, processor, memory, timing controller,touch sense IC, wireless controller, communications IC, etc. Asillustrated, the additional IC chips 334 may be located on the backsurface of the display substrate directly behind the display area 301.In the embodiment illustrated in FIG. 7A, a driver IC 330 is located onthe front surface 303 of the display substrate 302. The driver IC 330may be in electrical connection with the through vias 304 which in turnare in electrical communication with the wiring 310 in RDL 308 on theback surface 305 of the display substrate 302. In the embodimentillustrated in FIG. 7B, a driver IC 330 is located on the back surface305 of the display substrate 302, and in electrical communication withthe through vias 304. In the embodiment illustrated in FIG. 7A, thedriver ICs 330 are formed on the top surface of the display substrate302 reserved for the contact ledge 311. In the embodiment illustrated inFIG. 7B, the drive IC 330 is at least partially located directly behindthe display area 301. In either configuration, the driver IC 330communicates with the working circuitry 316 similarly as with aconventional OLED display.

FIG. 8 is a schematic front view illustration of a TFT display substrateand display module including an array of LEDs and a plurality of throughvias in accordance with an embodiment of the invention. The particularembodiment illustrated in FIG. 8 is similar to that previouslyillustrated in FIG. 4, with a TFT display substrate including workingcircuitry 316 replacing micro chips 216. In an embodiment, through vias304 can be formed through the display substrate directly behind thedisplay area 301.

FIG. 9 is a schematic front view illustration of a wearable electronicdevice including a display panel in accordance with an embodiment of theinvention. The wearable electronic device 400 may be any of a number ofwearable accessory products that include a display panel 215, 315, andin particular a flexible display panel 215, 315. The flexible displaypanel 215, 315 may be formed in any of the display modules describedabove. In an embodiment, the flexible display panel 215, 315 does notinclude a contact ledge 111, which may allow for increased allocationspace to the display area 201.

In one embodiment, the wearable electronic device is a smartwatchincluding a watch face 402, band 404, and clasp 406. A flexible displaypanel 215, 315 may be integrated into the smartwatch so that it spansboth the watch face and band. In this manner, the flexible display panel215, 315 can be adjusted to the contour of a user's arm. In accordancewith embodiments of the invention, a bezel 410 width surrounding thedisplay panel 215, 315 can be minimized, for example below 4-5 mm oreven less than 1 mm, less than 0.5 mm, or eliminated. Thus, the bezel210 design of the smartwatch can be designed for aesthetic concernsrather than as a requirement for allocating space for a contact ledge.

FIGS. 10-12 are perspective view illustrations of a wearable electronicdevice displaying various display images in accordance with embodimentsof the invention. In the embodiment, illustrated in FIG. 10, thewearable electronic device 400 is illustrated with a blacked out displayarea of the display panel 215, 315. For example, this may indicate astate in which the display panel is turned off. FIGS. 11-12 illustratestates of where the display panel is displaying different images. Forexample, FIG. 11 may display a watch design A, including watch face andband and FIG. 12 may display a watch design B, including a watch faceand band. Any number of displayed images are possible.

FIG. 13 illustrates a system diagram of an embodiment of wearabledisplay module 1300. For example, the wearable display module 1300 maybe incorporated into the wearable electronic devices of FIGS. 10-12, andinclude any of the flexible display panels described herein. The module1300 includes a processor 1302 and memory 1303 for managing the wearableelectronic devices and executing or interpreting instructions andcommands for the wearable electronic devices. The processor 1302 can bea general-purpose processor or a microcontroller for controlling thewearable electronic devices. The memory 1303 can be integrated withinthe processor 1302, or coupled to the processor 1302 via a memory bus.The memory 1303 includes nonvolatile storage, such as flash memory, andcan additionally include read only memory (ROM), and a form of volatilerandom access memory (RAM). In one embodiment, the processor 1302includes media decode capability, to display encoded content via aflexible display panel 1304. In one embodiment, the module 1300 includesa graphical user interface (GUI) manager 1306, to control informationthat is provided to and displayed on the flexible display panel 1304.

The module 1300 also includes a communication module 1308 thatfacilitates communication between the module 1300 and other electronics.In one embodiment, the communication module 1308 includes a module toprovide connectivity via universal serial bus (USB). The communicationmodule 1308 can further include wireless transceivers for Bluetooth, orWLAN connectivity, and can additionally include one or more WWANtransceivers to communicate with a wide area network including acellular data network.

In one embodiment, the module 1300 includes an accessory manager 1310that operates to authenticate and acquire data from an additionalelectronic device that can be coupled to the module 1300. In oneembodiment, the module 1300 is an accessory to a primary display device,and the accessory manager 1310 facilitates the connection of theadditional electronic device to the module 1300. In one embodiment, themodule 1300 may have accessory devices that are managed by the accessorymanager 1310, which facilitates the transfer of data to and fromaccessory devices.

In an embodiment, memory 1303 includes non-transitory computer-readablemedium stores instructions which, when executed by processor 1302, causethe processor to perform operations to adjust display data for aflexible display panel 1304 of the module 1300. In an embodiment, theoperations including receiving input from a control device, the inputincluding data for the flexible display panel, parsing the input toderive the data for display, and displaying the derived data on theflexible display panel. In an embodiment, the operations further includereceiving a configuration of the flexible display panel of the watchface and band, receiving a design from the derived data, (e.g. type ofwatch design including a watch face and watch band), and updating theflexible display panel spanning the watch face and watch band of thesmartwatch with the received design.

In an embodiment, an accessory manager is coupled to the flexibledisplay substrate 1304 to receive input from a control devicecommunicatively coupled to the module 1300. A graphical user interface(GUI) manager is coupled to the display substrate, to controlinformation displayed on the display substrate, where the displaysubstrate includes a first display area associated with a face of thewearable electronic device and a second display area associated with aband of the wearable electronic device. In an embodiment, the GUImanager provides a watch face design to the first display area and awatch band design to the second display area. In an embodiment, theaccessory manager receives input data from a control device via acommunication module, the input data including configuration data forthe GUI manager.

FIG. 14 is schematic cross-sectional side view illustration of a system1400 including a flexible display panel 1500 secured to a spool 1410 inaccordance with an embodiment of the invention. FIG. 15 is a schematiccross-sectional side view illustration of a flexible display panel 1500including an array of LEDs 214 and micro chips 216 in a display area ona front surface 203 of the display substrate 202 in accordance with anembodiment of the invention. The display panel 1500 illustrated in FIGS.14-15 may be similar to any of the display panels previously describedabove. In the embodiment illustrated in FIGS. 14-15, the flexibledisplay panel 1500 is rollable into and out of a housing 1420. In suchan embodiment, rather than locating the driver ICs 1430 additional ICchips 1434 and battery 1438 on the back surface 205 of the displaysubstrate 202, any combination of these components can be located withinthe housing 1420, such as on the spool 1410. In other embodiments, anyof these components may also be located on the back surface 205 of thedisplay substrate. For example, a thin film battery 1438 can be locatedon the back surface, or a plurality of batteries 1438 can be located onthe back surface. Likewise one or more driver ICs 1430 may be located onthe back surface to reduce transmission line distance to the micro chips216.

In an embodiment, the micro chips 216 may include ambient light sensorsto measure the ambient light striking the display area of the flexibledisplay panel 1500. Referring to FIG. 16, a schematic front viewillustration is provided of a flexible display panel 1500 including twoareas of micro chips 216A, 216B exposed to different levels of ambientlight in accordance with an embodiment of the invention. In anembodiment, area 216B of micro chips 216 is exposed to a greater amountof light than area 216A, for example, glare from a window within adisplay room. In such an embodiment, a processor or ambient lightcontroller in the system 1400 may increase the amount of light beingemitted from the LEDs 214 operated by the micro chips 216 in area 216Bin order to compensate for the ambient light.

FIG. 17 illustrates a system diagram 1700 for an embodiment of a displaysystem (e.g. a television) including a flexible display panel 1710described herein, including the system and display panels described withregard to FIGS. 14-16. The display system 1700 includes a processor 1720and memory 1704 for managing the system and executing instructions. Thememory includes non-volatile memory, such as flash memory, and canadditionally include volatile memory, such as static or dynamic randomaccess memory (RAM). The memory 1704 can additionally include a portiondedicated to read only memory (ROM) to store firmware and configurationutilities. In an embodiment, the processor 1720 manages ambient lightcorrection of the flexible display panel 1710 by controlling each microchip 216 output to LED devices 214 where light output is adjusted basedon light sensor data from a sensor controller 1770. Alternatively, suchan ambient light correction module 1705 can be located on each of themicro chips 216 within the display panel 1710.

The system also includes a power module 1780 (e.g., flexible batteries,wired or wireless charging circuits, etc.), a peripheral interface 1708,and one or more external ports 1790 (e.g., Universal Serial Bus (USB),HDMI, Display Port, and/or others). In one embodiment, the displaysystem 1700 includes a communication module 1712 configured to interfacewith the one or more external ports 1790. For example, the communicationmodule 1712 can include one or more transceivers functioning inaccordance with IEEE standards, 3GPP standards, or other communicationstandards, and configured to receive and transmit data via the one ormore external ports 1790. The communication module 1712 can additionallyinclude one or more WWAN transceivers configured to communicate with awide area network including one or more cellular towers, or basestations to communicatively connect the display system 1700 toadditional devices or components. Further, the communication module 1712can include one or more WLAN and/or WPAN transceivers configured toconnect the electronic device 1700 to local area networks and/orpersonal area networks, such as a Bluetooth network.

The display system 1700 can further include a sensor controller 1770 tomanage input from one or more sensors such as, for example, proximitysensors, ambient light sensors, or infrared transceivers. In anembodiment, the array of micro chips 216 on the display panel includesan array of light sensors in communication with the sensor controller.Each micro chip 216 may include a light sensor, or only portion of thearray of micro chips includes light sensors. For example, the array oflight sensors can be uniformly distributed in the array of micro chips.In one embodiment the system includes an audio module 1731 including oneor more speakers 1734 for audio output and one or more microphones 1732for receiving audio. In embodiments, the speaker 1734 and the microphone1732 can be piezoelectric components. The electronic device 1700 furtherincludes an input/output (I/O) controller 1722, a display screen 1710,and additional I/O components 1718 (e.g., keys, buttons, lights, LEDs,cursor control devices, haptic devices, and others). The displaydevice/screen 1710 and the additional I/O components 1718 may beconsidered to form portions of a user interface (e.g., portions of thedisplay system 1700 associated with presenting information to the userand/or receiving inputs from the user).

In utilizing the various aspects of this invention, it would becomeapparent to one skilled in the art that combinations or variations ofthe above embodiments are possible for forming flexible display panelsand system applications including the flexible display panels. Althoughthe present invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or acts described. The specificfeatures and acts disclosed are instead to be understood as particularlygraceful implementations of the claimed invention useful forillustrating the present invention.

What is claimed is:
 1. A display module comprising: a display substrateincluding a front side and a back side; an array of light emittingdiodes (LEDs) on the front side of the display substrate; an array ofmicro chips bonded to the front side of the display substrate andinterspersed among the array of LEDs; a plurality of wiring layers thatinterconnect the array of LEDs to the array of micro chips, wherein eachmicro chip is connected to one or more LEDs; and a plurality ofinterconnects that are electrically connected to the array of microchips and extend through the display substrate from the front side tothe back side.
 2. The display module of claim 1, wherein each LEDcomprises an inorganic semiconductor.
 3. The display module of claim 2,each LED is a vertical LED.
 4. The display module of claim 3, furthercomprising a passivation layer over the front side of the displaysubstrate, wherein the passivation layer laterally surrounds the arrayof LEDs and the array of micro chips.
 5. The display module of claim 4,further comprising a transparent conductor layer spanning over thepassivation layer and electrically connected to the array of LEDs. 6.The display module of claim 5, further comprising an encapsulation layerformed over the transparent conductor layer.
 7. The display module ofclaim 5, wherein the transparent conductor layer is connected to onemore of the plurality of interconnects.
 8. The display module of claim5, wherein each LED has a maximum dimension of 1 to 100 μm.
 9. Thedisplay module of claim 8, wherein each micro chip has a maximumdimension of 1 to 300 μm.
 10. The display module of claim 8, wherein theplurality of interconnects comprises a plurality of interconnect linesand a plurality of vias.
 11. The display module of claim 8, furthercomprising one or more chips on the back side of the display substrate.12. The display module of claim 11, wherein the one or more chips areelectrically connected to the plurality of interconnects that extendthrough the display substrate from the front side to the back side. 13.The display module of claim 1, wherein each micro chip is connected to aplurality of LEDs.
 14. The display module of claim 13, wherein eachmicro chip is connected to a plurality of pixels.
 15. The display moduleof claim 14, wherein each micro chip is connected to a plurality of LEDswithin each pixel to which the micro chip is connected.
 16. The displaymodule of claim 15, wherein the array of micro chips includes a row ofmicro chips arranged between rows of LEDs.
 17. The display module ofclaim 16, wherein each LED has a maximum dimension of 1 to 100 μm, andeach micro chip has a maximum dimension of 1 to 300 μm.
 18. The displaymodule of claim 17, wherein the plurality of interconnects comprises aplurality of interconnect lines and a plurality of vias.
 19. The displaymodule of claim 18, further comprising one or more chips on the backside of the display substrate.
 20. The display module of claim 19,wherein the one or more chips are electrically connected to theplurality of interconnects that extend through the display substratefrom the front side to the back side.